The present invention relates to a cooling system and method for thermal management of an engine in a vehicle, and more particularly to a diesel engine in a vehicle.
Conventionally, a cooling system for a diesel engine in a vehicle includes a water pump, for pumping a liquid coolant through the system, a radiator for cooling the coolant, and an oil cooler for cooling oil used by the engine. A fan is also typically provided to draw air through the radiator in order to enhance the cooling effect of the radiator. The coolant is also typically routed through a heater core in order to provide heat for the vehicle passenger compartment, when needed, as well as being routed through an exhaust gas recirculation (EGR) cooler.
The water pump and the fan are typically driven off of the engine crankshaft, so their speed is strictly a function of the engine speed. Consequently, when the engine is started cold, a pair of thermostats, one upstream of the radiator and one upstream of the oil cooler, are needed to block the flow through the radiator and oil cooler, respectively, in order to maintain as much heat in the system as possible until the coolant and oil have heated up to their respective operating temperatures. As each comes up to temperature, its thermostat opens and the flow continues strictly as a function of engine speed. But the routing of the coolant and the amount of coolant flow are not a function of any other vehicle or engine parameters that are important to maintaining the desired engine temperature. Moreover, there is a relatively large number of components employed to create this cooling system with limited ability to accurately control the engine temperature.
Thus, it is desirable to have a diesel engine cooling system that overcomes the drawbacks of conventional engine cooling systems. In particular, it is desirable to have a system with the ability to more accurately provide the desired engine coolant and oil cooling, while minimizing the number of components required for the system.
In its embodiments, the present invention contemplates a cooling system for a diesel engine, having a coolant inlet and a coolant outlet, in a vehicle. The cooling system has a coolant circuit adapted to operatively engage the coolant inlet and coolant outlet, and a pump operatively engaging the coolant circuit to pump a coolant therethrough. The cooling system also includes a radiator operatively engaging the coolant circuit, an oil cooler operatively engaging the coolant circuit, and a heater operatively engaging the coolant circuit. A valve has a first valve port adapted for receiving coolant from the engine, a second valve port for selectively receiving coolant from the oil cooler, a third valve port for selectively routing coolant to the radiator, and a fourth valve port for selectively routing coolant to the heater, and with the valve being controllable to selectively control the routing of the coolant through the valve ports. The cooling system also has a control module electrically coupled to the valve for electronically controlling the valve to thereby control the routing of the coolant through the valve ports.
The present invention further contemplates a method of controlling an engine temperature of a diesel engine in a vehicle, with the diesel engine having a coolant circuit including a water pump, a flow control valve, and a radiator, an oil cooler, and a heater each operatively connected to the flow control valve, the method comprising the steps of: detecting a plurality of operating conditions; determining if the operating conditions are within a first mode, a second mode, a third mode, a fourth mode, a fifth mode, or a sixth mode of operation; adjusting the flow control valve to substantially prevent routing of coolant through the radiator and allow for routing of coolant through the heater and the oil cooler if the operating conditions are in the first mode; adjusting the flow control valve to substantially prevent routing of coolant through the radiator and the oil cooler and allow for routing of coolant through the heater if the operating conditions are in the second mode; adjusting the flow control valve to allow for routing of coolant through the radiator, the heater and the oil cooler if the operating conditions are in the third mode; adjusting the flow control valve to substantially prevent routing of coolant through the heater and allow for routing of coolant through the radiator and the oil cooler if the operating conditions are in the fourth mode; adjusting the flow control valve to substantially prevent routing of coolant through the radiator and the heater and allow for routing of coolant through the oil cooler if the operating conditions are in the fifth mode; and adjusting the flow control valve to substantially prevent routing of coolant through the radiator, the heater and the oil cooler if the operating conditions are in the sixth mode.
An advantage of the present invention is that there is a smaller number of components used in the diesel engine cooling system as compared to a conventional system. A single valve selectively controls the amount of coolant flow if any through the radiator, oil cooler and other heat exchangers.
Another advantage of the present invention is that the amount of coolant flowing through the radiator can be more precisely controlled, thus allowing for more accurate control of the coolant temperature, and hence, engine temperature.
A further advantage of the present invention is that the amount of coolant provided to the oil cooler can be controlled, thus allowing for more accurate control of the oil temperature.